Three closely related projects are proposed (I) Cultured murine peritoneal exudative and alveolar macrophages will be incubated in the presence of aqueous cigarette smoke extracts. Considered in the study will be the effects of incubation time and cigarette smoke concentration on elastase secretion and cell viability. (II) Human alveolar macrophages will be cultured to determine whether or not they secrete alpha-2-macroglobulin in vitro. Secretion will be evaluated by the autoradio-immunoelectrophoretic detection of 35S methionine incorporation into the secreted inhibitor. The secretion of macrophage alpha-2-macroglobulin will also be examined in terms of its interaction with macrophage elastase. (III) Murine macrophage elastase will be purified from the conditioned medium of macrophages cultured in the absence of serum. The enzyme will be purified by affinity chromotography. The purified enzyme will be characterized chromatographically and electro-phoretically as well as by its interaction with a variety of natural occurring and synthetic substances and inhibitors.